Cell experiment:

hESC cultures are obtained in mTeSR-1 medium and expanded with daily medium exchange until colonies reach the desired level of confluence (~70% to 80%). At this time (marked day 0), mTeSR-1 is replaced with a basal medium comprised of RPMI 1640 medium supplemented with 2% B27 supplement and 1% penicillin/streptomycin. 20 ng/mL BMP-4 and/or 6 ng/mL activin A are added to the basal medium for primitive streak induction, and exchanged daily until day 3. Then, basal media with or without 5 mM IWP-4 is added to the cells and exchanged every 2 days [dimethyl sulfoxide (DMSO) at the same concentration is used as a vehicle control] until day 15, after which basal medium is supplied every 2 days[1].

IWP-4 is a small molecule Wnt inhibitor with an IC50 of 25 nM.

IWP-4 is a small molecule Wnt inhibitor with an IC50 of 25 nM. IWP-4 induces the expression of cardiac markers, including cardiac troponin I (CTNI) and cardiac myosin heavy chain bright cells (MYHhi +). IWP-4 also results in the appearance of beating foci (0.44±0.10 SEM beats per second), which is absent in all cultures not receiving IWP-4. Further, flow cytometric analysis shows that there are significantly more MYHlo + cells in IWP-4 treated cultures (PAXIN2, CTNNB1 and GSK3B as compare to osteogenic medium alone on day 7, but MPCs treated with IWP-4 express elevates levels of DKK1 and GSK3β on day 21. IWP-4 also causes a significant down regulation of SPARC and COL1A1[2].

References:
[1]. Hudson J, et al. Primitive cardiac cells from human embryonic stem cells. Stem Cells Dev. 2012 Jun 10;21(9):1513-23.
[2]. Frith JE, et al. Microbioreactor array screening of Wnt modulators and microenvironmental factors in osteogenic differentiation of mesenchymal progenitor cells. PLoS One. 2013 Dec 23;8(12):e82931.